biological explanation of aggression - brain structure Flashcards
(16 cards)
What does the prefrontal cortex do and where is it?
This part of the cerebral cortex right at the front of the frontal lobe
regulates behaviour and governs social interaction. Gives us the ability to delay gratification of an impulse by inhibiting (suppressing) messages from the amygdala
What is the prefrontal cortex link with aggression?
Raine (1997) - our classic study - found abnormally low metabolism in the prefrontal cortex of murderers compared to matched control group
What is the evidence/case study for prefrontal cortex?
PHINEAS GAGE
Railway worker in the USA - in 1848 he suffered an accident when an iron rod set off an explosive and it blew straight through Gage’s face and out the top of his head
For the remaining years of his life, people say his personality had changed as he became irresponsible and aggressive.
It was the damage to his prefrontal cortex which caused this.
Where is the hypothalamus and what does it do?
The hypothalamus is part of the limbic system
It maintains homeostasis (stability of the body)
What is the hypothalamus link with aggression?
This is linked to aggressive behaviour in males via the production of testosterone
What is the evidence for the hypothalamus?
Animal experiments using cats (Flynn et al. 1970)
Electrical stimulation of the hypothalamus and cats produces an aggressive response, including hissing and growling. Stimulation of different parts results in different types of aggression E.G stimulation to the dorsal hypothalamus (at the back) produced defensive behaviour which is shown by animal in response to threat or attack
Where is the amygdala and what does it do?
The amygdala is part of the limbic system
This is the centre for emotions, emotional behaviour and motivation
What is the amygdala link with aggression?
The reactivity of the amygdala in humans is proven to be an important predictor of aggressive behaviour
What is the evidence for the amygdala?
Texas owed shooting of 1966 in which Charles Whitman, a student and ex-marine, fired down from the clock tower on the campus of the university of Texas, killing 14 people and wounding 31 others. Earlier in the day, Whitman had killed his wife and mother.
Whitman was suffering from feelings of rage, confusion, and violent impulses, which he documented exhaustively in writing
He had a tumour which pushed against the amygdala region of his brain
Animal experiments using cats
Making lesions to the amygdala in cat produces aggressive behaviour (bard 1940)
If the amygdala is stimulated using an electric current then the animal displays aggression
If the amygdala is removed, then the animal becomes passive and unresponsive and does not show a fair response to stressors
The role of serotonin and dopamine
- what does it do
Normal levels of serotonin in the OFC are associated with a reasonable degree of behavioural self control. Decreased serotonin may disturb this and reduce self-control, leading to more impulsive behaviours.
Serotonin and dopamine link with aggression
Serotonin under activity stimulates dopamine over activity and both are linked with impulsivity and aggression
Evidence for serotonin and dopamine link
Research has shown levels of serotonin breakdown product were lower in violent impulsive offenders compared to non violent offenders.
EVIDENCE
There is evidence to support the role of the brain in the development of aggression e.g animal experiments using cats. E.g Flynn showed direct stimulation of the hypothalamus lead to sham rage. This shows that the hypothalamus has a role to play in aggressive behaviour
CA
However, there are issues with using animals in psychological research
Yet, the argument is further supported by research and evidence using humans e.g Charles Whitman/Phineas Gage
CA
However, the problems with using individual cases with brain damage is that they are not generalisable
APPLICATION
Law e.g finding individuals not guilty by reason of insanity
Reductionist as it only looks at brain structure and not other affecting factors
STRENGTHS AND SHORTCOMINGS
It can be difficult to isolate areas of the brain responsible for aggression. The brain is very complex and so it is hard to measure the impact of connected areas on the development of aggression
However, scientific methods are used e.g PET scan to provide an objective measure to areas of the brain which may have some impact on aggression
The explanation is, however reductionist e.g it provides simple organic causation for aggression
That said, it is important to be reductionist as it is difficult to research and theories on all behaviours that lead to aggression
ALTERNATIVE
The theory does not take into account the role of nurture e.g social learning theory would suggest that we learn behaviour through observing a role model and imitating this behaviour for a similar reward.
This means that this theory of aggression is somewhat incomplete.
